Lamp base



FIG. 1 is a front perspective view of a lamp base showing my new design, the broken lines being shown for illustrative purposes only.

FIG. 2 is a front elevational view thereof.

FIG. 3 is a right side elevational view thereof, the left side being substantially identical thereto.

FIG. 4 is a top plan view thereof.

FIG. 5 is a bottom plan view thereof.

FIG. 6 is a rear elevational view thereof. 

The ornamental design for a lamp base, substantially as shown and described. 